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UCSB’s Ben Monreal Says Risk of Significant Radiation Is ‘Flat Zero’

Assistant physics professor says it's not the level of radiation but the intensity of exposure that counts

UCSB assistant physics professor Ben Monreal was at a conference in Germany when this month’s earthquake struck in Japan. Wanting to help in some way after the disaster, he hopes to ease fears by reaching out and teaching people about radiation.

UCSB assistant physics professor Ben Monreal was at a conference in Germany when this month’s earthquake struck in Japan. Wanting to help in some way after the disaster, he hopes to ease fears by reaching out and teaching people about radiation.  (Lara Cooper / Noozhawk photo)

By Alex Kacik, Noozhawk Staff Writer | @NoozhawkBiz |

It’s a memory most will remember until they die. UCSB assistant physics professor Ben Monreal was at a conference in Germany when he first heard news of March 11’s 9.0-magnitude earthquake in Sendai, Japan.

“I was in the back of room reading The New York Times on my laptop when I read the first headline, ‘9.0 Earthquake Hits Japan,’” Monreal said. “There was someone at the conference who has family in the Sendai area. It made me want to get involved immediately.”

But for the time being, all he could do was read and watch. It wasn’t until the tsunami struck and the state of the nuclear power plants overshadowed the natural disasters that Monreal felt he could contribute.

“Hearing about the panic and fear in places far (from Japan) is irrational and unnecessary,” he said, “and I hope teaching people more about how radiation works will save them some stress and energy that they could use in a positive manner.”

Monreal received his undergraduate degree from Yale University, where a nuclear physics lab instructor inspired him to pursue physics through graduate school at MIT. After working as an intern at Lawrence Berkeley National Laboratory, he continued his research in particle physics and astrophysics at UCSB.

He started by explaining the levels of radiation. He says everyone has some level of radiation — it could be from food or the atmosphere — but it’s the intensity of exposure that’s important.

“You could see the radiation dosage increase from someone moving from Santa Barbara to Montecito or Carpinteria because certain base rock is more radioactive than others,” Monreal said. “Even if radiation levels are detectable on the West Coast, that has nothing to do with whether people should worry.”

Radiation is measured in units per hour called sieverts, while a millisieverts is one-thousandth of a sievert and a microsievert is a millionth. Five sieverts per hour of radiation is lethal, he said, while most people experience a handful of millisieverts a year.

“The vast majority of people in Japan don’t even have a shot of getting a millisievert per hour,” Monreal said.

The longer a gas sticks around, the more benign it is, Monreal said, but it’s the gases that don’t last long that are worrisome. Therefore, the chances of any significant levels of radiation reaching California is “flat zero,” he said.

“It will certainly spread in detectable ways to Tokyo and Tokai, but how much will it spread in harmful ways is unknown,” Monreal said. “Even gases in a jet stream are diminishing and are not perfectly intact parcels, so the chances of it getting to California is zero.”

Radiation has manifested in Tokyo. While officials declared Tokyo’s water safe on Thursday, authorities in the city’s suburbs discovered water supplies with radioactive iodine nearly three times the normal level for infants. But Monreal says radiation spreading farther than that is unlikely if people are careful.

The United States has tested thousands of nuclear explosions over the years, and while scientists monitored how radiation spread, he says there was no “magic plume that carried it long distances.”

Fukushima’s fourth reactor container is leaking some of the water used to cool the core, but there is only significant levels of radiation when that water mixed with fuel catches on fire and smoke is released.

“When a reactor is on fire and spewing stuff, people at the reactor — if they are not careful — can have doses on sievert scale,” Monreal said. “Thirty kilometers away, people are at risk, but if people stay inside, it really does help.”

The biggest determinant on the intensity of the radiation emitted will be how much the fuel rods catch on fire, Monreal said. There has been smoke coming out of several of the reactors, but officials are unsure what caused it. Workers were temporarily evacuated, and work in the plant had been slowed as of Thursday night.

“The dose rates would’ve been 400 millisieverts per hour for workers during the biggest spike, but the fire didn’t last long and the dose rate wasn’t high for a long period of time,” Monreal said.

He said that in comparison to Chernobyl and Three Mile Island, Japan was much better prepared. In Chernobyl, the reactor was still fissioning when there were explosions and smoke, and there was no containment vessel. While that contributed to high exposure levels to those immediately nearby, Monreal said the biggest problem with Chernobyl was that people weren’t notified of the radiation, and the consumption of contaminated food resulted in a worst-case scenario.

“What the decontamination team will worry about is getting rid of the cesium and strontium from the topsoil” — like in Chernobyl when workers got rid of 99 percent of the radiation by disposing of the top 10 centimeters of the soil, he said. “The long-term outlook for this area of Japan is perfectly fine. There won’t be large chunks of uninhabitable land.”

He said that unlike Chernobyl, Fukushima and surrounding areas were immediately evacuated and people are careful to avoid any exposure by staying inside and cleaning. At Three Mile Island, gases such as xenon, radon and krypton were released in the steam, but no one was harmed or killed by the potentially deadly gases.

“It was horribly mismanaged and the reactor did melt down, but there was not large-scale radiation release that actually hurt anybody,” he said.

He said he hopes the most recent crisis doesn’t turn people off of nuclear power plants because modern designs are much safer and reliable.

“The vast majority of radiation people are putting into the atmosphere is from coal-powered plants’ smoke stacks,” Monreal said. “People who want to stop nuclear plants, that choice is increasing everyone’s radioactive dose while destroying the environment by climate change,” which at this rate may be beyond saving in five years, he added.

Although nothing bad can be said about solar power, Monreal said it has not progressed enough to rely on.

Click here for a map to monitor radiation readings. Instead of sieverts, it’s measured in roentgen. The normal amount of roentgen is 5 to 20 uR/hr, or microroentgens per hour. Five hundred millisieverts would equal 50 milliroentgens.

“Higher radiation readings does not mean there is an increased health risk,” Monreal said. “It means it reads the tiniest changes in readings.”

He said what the United States needs to worry about are safety standards for nuclear power plants, especially the one in San Onofre.

“Is this thing prepared for a tsunami; let’s ask that question and make sure we have answers,” Monreal said. “The answer should probably not be let’s get rid of it, but maybe move the containment vessel higher up.”

Noozhawk staff writer Alex Kacik can be reached at .(JavaScript must be enabled to view this email address). Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Become a fan of Noozhawk on Facebook.




comments powered by Disqus

» on 03.25.11 @ 01:44 PM

OMG!!!! What will the news media do now?!?!! How will Lois
Capps knee jerk this news? How will the anti nuke hysterical spin more fear and loathing from this?

Answer – The news media will ignore science and make up terror on its own.

Lois will knee jerk anyway and so hard she will kick her own butt.

The anti nuke people will just say “remember TMI!”

» on 03.25.11 @ 02:21 PM

Thanks Prof. (and Noozhawk).  I finally feel like I’ve gotten some relevant, helpful, and trustworthy information in layman’s terms regarding the radiation risk to the people of Japan and beyond.  No hype, just reliable, useful info.  I appreciate it.

» on 03.25.11 @ 05:36 PM

Prof. Monreal gave an excellent, very accessible lecture at UCSB on this topic. It is available online at http://online.kitp.ucsb.edu/online/plecture/bmonreal11/rm/flashtv.html or at http://online.kitp.ucsb.edu/online/plecture/bmonreal11/.

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